Background. Obesity and obesity-associated conditions have been shown to greatly decrease both quality of life and life expectancy. Currently, bariatric surgery is the only proven treatment for sustained weight loss in the morbidly obese patient. However the decision to undergo surgery is a difficult one because of the risks involved in surgery and the uncertain outcome. Objectives. As an outcomes researcher with an interest in decision analysis, the specific objectives of this application are to: a) broaden my skills in the construction of decision analytic models, the decision sciences, and the conduct of patient-oriented research and b) use these skills to develop and test an interactive decision support tool that provides tailored information about the individual patient's surgical risk and the expected benefit of bariatric surgery. My long- term career goal is to develop and test a variety of patient-specific decision support tools for patients with morbid obesity. Training. For my career development, I plan to take additional coursework in the decision sciences, focusing on the design of decision analytic models for simulations. My mentorship team is comprised of leading experts in the fields of decision analysis, obesity and research methodology: Mark H. Eckman, MD, MS, Joel Tsevat, MD, MPH, David D'Alessio, MD, David Fischer, MD, David Arterburn, MD, MPH, Richard Hornung, DrPH, Thomas Inge, MD, PhD, and Meg Zeller, PhD. Research Design. For this proposal, we will first develop a population based decision analytic model that examines two strategies: bariatric surgery versus the natural history of morbid obesity. Using this model we will identify those patients for whom the decision to have bariatric surgery is a "close call". This model will then be the basis for the development of a patient-specific model that will serve as the foundation for our decision support tool. Using a randomized controlled trial, we will assess patients'understanding of the risks and benefits of bariatric surgery, decisional conflict, satisfaction with the decision making process and decision self efficacy when using the decision support tool compared to a control group with access to generic information about bariatric surgery. Relevance. At the completion of this project, we will have developed and tested an interactive web-based decision support tool to be used by morbidly obese patients considering bariatric surgery. This will assist patients in making a more informed decision when weighing the treatment options for morbid obesity.